1. Field of the Invention
This invention relates to a radiation image storage panel and a process for the preparation of the same. More particularly, this invention relates to a radiation image storage panel comprising a support and a phosphorcontaining resin layer provided thereon in which a resinous binder and a stimulable phosphor are contained in a weight ratio of 1:1 to 1:100, and a process for the preparation of the same.
2. Description of Prior Arts
For obtaining a radiation image, there has been conventionally employed a radiography utilizing a combination of a radiographic film having an emulsion layer containing a photosensitive silver salt material and a radiographic intensifying screen.
As a method replacing the above-described radiography, a radiation image recording and reproducing method utilizing a stimulable phosphor as described, for instance, in U.S. Pat. No. 4,239,968, has been recently paid much attention. In the radiation image recording and reproducing method, a radiation image storage panel comprising a stimulable phosphor (stimulable phosphor sheet) is used, and the method involves steps of causing the stimulable phosphor of the panel to absorb radiation energy having passed through an object or having been radiated by an object; exciting the stimulable phosphor with an electromagnetic wave such as visible light and infrared rays (hereinafter referred to as "stimulating rays") to sequentially release the radiation energy stored in the stimulable phosphor as light emission; photo-electrically processing the emitted light to give electric signals; and reproducing the electric signals as a visible image on a recording material such as a photosensitive film or on a displaying device such as CRT.
In the above-described radiation image recording and reproducing method, a radiation image can be obtained with a sufficient amount of information by applying a radiation to the object at considerably smaller dose, as compared with the case of using the conventional radiography. Accordingly, this radiation image recording and reproducing method is of great value especially when the method is used for medical diagnosis.
The radiation image storage panel employed in the above-described radiation image recording and reproducing method has a basic structure comprising a support and a stimulable phosphor-containing resin layer provided on one surface of the support. Further, a transparent film is generally provided on the free surface (surface not facing the support) of the stimulable phosphor-containing resin layer to keep the stimulable phosphor-containing resin layer from chemical deterioration or physical shock.
The stimulable phosphor-containing resin layer comprises a resinous binder and stimulable phosphor particles dispersed therein. The stimulable phosphor-containing resin layer is generally provided on a support under an atmospheric pressure utilizing the following coating procedure.
The stimulable phosphor particles and the resinous binder are mixed in an appropriate solvent to prepare a coating dispersion. The coating dispersion is directly applied onto a surface of a support for a radiation image storage panel under an atmospheric pressure using a doctor blade, a roll coater, a knife coater or the like, and the solvent contained in the coating dispersion applied is removed to form a stimulable phosphor-containing resin layer. Alternatively, the stimulable phosphor-containing resin layer is provided on the support by applying the coating dispersion onto a false support such as a glass plate under an atmospheric pressure, removing the solvent from the coating dispersion to form a phosphor-containing resin film, separating the film from the false support, and then causing the film to adhere to the genuine support.
When excited with stimulating rays after having been exposed to a radiation such as X-rays, the stimulable phosphor particles contained in the stimulable phosphor-containing resin layer emit light (stimulated emission). Accordingly, the radiation having passed through an object or having been radiated by an object is absorbed by the stimulable phosphor-containing resin layer of the radiation image storage panel in proportion to the applied radiation dose, and a radiation image of the object is produced in the radiation image storage panel in the form of a radiation energy-stored image (latent image). The radiation energy-stored image can be released as stimulated emission (light emission) by applying stimulating rays to the panel, for instance by scanning the panel with stimulating rays. The stimulated emission is then photo-electrically converted to electric signals, so as to produce a visible image from the radiation energy-stored image.
It is desired for the radiation image storage panel employed in the radiation image recording and reproducing method to have a high sensitivity and to provide an image of high quality (high sharpness, high graininess, etc.). In particular, from the viewpoint of obtaining more accurate and detailed information of an object, it is desired to develop a radiation image storage panel which provide an image of improved sharpness.